A majority of manuscripts transmitting the poetic works of Publilius Optatianus Porfirius include a pair of letters that present themselves, respectively, as an epistle from Constantine the Great to the poet, and from Porfirius to the emperor. Most scholars tend to accept their authenticity, as well as their usefulness as sources for reconstructing Porfirius’ life and poetic activity; nevertheless, doubts have been raised. These can be traced as early as Kaspar Barth in the mid-17th c., and appear most recently in the latest commentary (1973), which views the epistles as a scholarly exercise, and in the work of Smolak (1989). Against the authenticity of Constantine’s letter - which Kluge (1924) maintains was personally written by the emperor himself, rather than by his chancellery - one may note an epistle from Theodosius to Ausonius claiming to be the first time that an emperor had written personally and directly to a poet. More relevant, perhaps, are a series of chronological contradictions that one finds when comparing the two letters: that of Constantine speaks of an initial dispatch of carmina from the poet, while that of Porfirius refers to carmina which had already been sent on prior occasions. This would appear to suggest that the emperor’s letter preceded the poet’s, yet Porfirius’s epistle presents itself as the first contact between the two men, even as the emperor’s appears to show greater familiarity from the start.

The style of Constantine’s letter is quite different than what one finds being produced by the imperial chancellery in late antiquity, and a few of its more obvious imprecisions would be strange in a text written by the court at the start of the 4th c.: it speaks of the cothurni (buskins) used for comedy, frequently repeats the same words and conjunctions, and also includes certain grammatical errors that some editors have tried to remedy in various ways. The text comprises a series of loci communes (literary tropes): no one can hope to compete with Homer and Vergil, but all can compose poetry anyhow; theatrical works, elegies, and lyrics continue to be written; in some periods the state values poets less, but they receive their proper due under a good emperor; and poetry is more difficult than prose because it needs to respect meter, a point of view from which Porfirius is truly deserving of merit, since he has added to the task’s usual difficulties the pleasure of a new and complicated technique, viz. the very difficult composition of versus intexti. [G. Polara; tr. C. L. Caterine].